Fix Docker image by updating Debian base and SSH setup

[sobrito]

This PR fixes the Docker build failure caused by using an unsupported Debian version (buster).

• Updated base image to a supported Debian version
• Fixed apt repository errors
• Switched to openssh-server
• Cleaned up Dockerfile

[what-the-diff]

PR Summary

• Upgraded Base Server Image
  In this change, we have updated the foundation of our server from debian:buster-slim to the newer debian:bookworm-slim. This brings various improvements including bug fixes and better performance.

• Specific SSH Server Installation
  We have adjusted our system installation to include openssh-server directly and removed the old ssh package. This gives us a more reliable and secure connection system.

• Optimized Image Size
  We've included a cleanup process after our server setup that deletes the APT list files. This reduces the total size of our server image, making it leaner and faster to deploy.

• Preparation for SSH Daemon
  Lastly, we created a specific directory (/var/run/sshd) to ensure the SSH daemon (the system that handles secure connections) can start and run properly.